Ash Basin Water Solutions Utilizing Horizontal Directional Well Installations
Horizontal directional drilling for non-traditional applications has its roots in the 1930’s oil field technology. In the 1970’s, the “river crossing” or HDD technology started in the central valley of California. In the late 1980’s a combination of oil field and river crossing technologies were utilized for environmental remediation activities. Since that time, HDD has been utilized for a wide variety of uses outside the traditional utility and pipeline industries. Nearly all environmental remediation remedies can be applied using HDD technology, however, successful uses of HDD for non-traditional activities requires proper engineering design along with an understanding of subsurface geologic conditions.
Coal combustion product (CCP) basins can leach contaminants into the groundwater. Horizontal wells have relatively recently begun to be utilized to mitigate liability created by large CCP basins.
In one application in the north central US, a horizontal dewatering well was installed in dry stacked ash basin to control the buildup and discharge of leachate from the basin. The well successfully lowered leachate levels and prevented uncontrolled discharge of fluids from the basin.
In another application, eight horizontal wells were installed at northern plains power plant. The wells are being used to inject or withdraw groundwater to control migration of leachate contaminated groundwater from the site.